In walls formed of plaster boards, sheet rock, plywood and other relatively thin or soft materials, problems can arise when attempting to mount objects to these walls, particularly transverse rods for draperies, drapes, lighting fixtures, picture frames and other objects which impose stress upon these walls. These walls can be incapable of receiving the aforementioned rods, fixtures and frames when held in place by standard screws and bolts. Thus, it has become common practice to use anchoring sockets of some sort in order to secure these objects to a wall. A number of wall anchors are noted in the prior art, particularly U.S. Pat. Nos. 4,646,998; 4,752,170; 5,409,339; 5,533,851; and 6,086,035.
Prior art wall anchors, or back clips as they are otherwise known, such as disclosed in U.S. Pat. No. 4,669,936, teach a back clip having a body portion with a hollow barrel therein and laterally expandable fingers in alignment with the hollow barrel. The fingers extend through a wall and upon receiving a bolt, pin, screw or other securing member through the barrel, the laterally expandable fingers expand against the inside portion of the wall.
Common wall anchors, such as the one taught by U.S. Pat. No. 4,669,936, have a straight channel separating the fingers. This channel is usually narrower than the hollow barrel portion, so that when the securing member is inserted, it expands the fingers, securing the wall anchor to the wall. When these fingers are expanded they necessarily bend or hinge at some point on the finger, usually at a point at or near where each finger is connected to the hollow barrel. This hinge portion of the fingers is thus normally under some amount of stress due to the deformation that takes place in the wall anchor when the bolt, pin or screw is introduced into the wall anchor. Because of this stress, harder, more rigid plastics, the most preferred material of construction for wall anchors, tend to break in this hinge area, particularly when used in cold-weather. Softer plastics are commonly used to avoid this breakage problem, but may correspondingly reduce the strength of the wall anchor.
Referring to FIG. 1, a prior art wall anchor 2 is shown. Wall anchor 2 of FIG. 1 includes a generally flat circular head 4 having a bore therethrough (not shown) for receiving a securing member, such as a bolt, pin, screw, nail or similar object (not shown). Wall anchor 2 also contains a barrel 6 having a bore therethrough (not shown) and a pair of symmetrical fingers 8a and 8b flexibly joined to the barrel 14 at its back end. A generally straight channel 10 separates the two symmetrical fingers 8a and 8b. FIG. 2A shows a view of the prior art wall anchor from the front, and, looking through the bore in head 4, channel 10 is visible between the two symmetrical fingers 8a and 8b.
FIG. 2B shows the prior art wall anchor 2 in its secured position in a wall 16. The bores through the barrel 6 and the head 4 receive a securing member, in this case a mounting pin 14, therethrough. When the mounting pin 14 is inserted into the wall anchor, the pin engages and spreads the fingers 8a and 8b apart. The portions 12a and 12b, where the fingers 8a and 8b attach to the barrel 6, are under a considerable amount of stress due to the deformation that takes place when the fingers are expanded.
It would thus be desirable to develop a wall anchor designed to reduce stress in the hinge portion of the fingers. This type of wall anchor would allow for the use of harder, more rigid plastics, resulting in a stronger anchor less susceptible to breakage.